This invention relates to electrical switches, and more specifically relates to a grounding switch for connecting electrical equipment or overhead power lines in a high voltage power transmission line to ground. Grounding switches are well known to the art, and typically are shown in U.S. Pat. Nos. 2,420,485 and 2,699,482 which are each owned by the assignee of the present invention.
Prior art grounding switches are not well adapted for handling high momentary currents or, in some cases, for handling normal momentary currents in extremely high voltage transmission systems, such as those rated at 345 kV to 765 kV. Therefore, additional mechanisms or special construction must be provided for grounding switches which increase their cost and increase the operating forces necessary to operate the switches if they are to be capable of handling high momentary currents.
The present system provides a novel toggle arrangement and counterbalancing arrangement for the movable blade of a grounding switch which permits the blade to telescope into its cooperating stationary jaw contact when the contacts move into engagement, thereby to provide improved resistance to the magnetic blowoff forces produced by high momentary currents. The counterbalance arrangement further reduces the amount of operating effort necessary to move the switch from its open and toward its closed position. Operating effort is further reduced by a novel toggle type construction for the blade, whereby the operating mechanism has an increased mechanical advantage over the last few degrees of movement of the blade to its engaged position.